President Trump picked Lt. Gen. H.R. McMaster, a widely respected military strategist, as his new national security adviser on Monday, calling him “a man of tremendous talent and tremendous experience.”

Mr. Trump made the announcement at his Mar-a-Lago getaway in Palm Beach, Fla., where he has been interviewing candidates to replace Michael T. Flynn, who was forced out after withholding information from Vice President Mike Pence about a call with Russia’s ambassador.

The choice continued Mr. Trump’s reliance on high-ranking military officers to advise him on national security. Mr. Flynn was a retired three-star general and Defense Secretary Jim Mattis is a retired four-star general. His first choice to replace Mr. Flynn, who turned the job down, and two other finalists were current or former senior officers as well.

Shortly before announcing his appointment, Mr. Trump wrote on Twitter: “Meeting with Generals at Mar-a-Lago in Florida. Very interesting!”

General McMaster is seen as one of the Army’s leading intellectuals, first making a name for himself with a searing critique of the Joint Chiefs of Staff for their performance during the Vietnam War and later criticizing the way President George W. Bush’s administration went to war in Iraq. ...